The invention relates to a process for the preparation of an aromatic hydrocarbon mixture from a mixture of carbon monoxide and hydrogen using a mixture of two catalysts of which one has the capability of catalysing the conversion of an H.sub.2 /CO mixture into acyclic oxygen-containing hydrocarbons, and the other is a crystalline silicate which has the capability of catalysing the conversion of acyclic oxygen-containing hydrocarbons into aromatic hydrocarbons.
It is known to prepare aromatic hydrocarbons from synthesis gas over a mixture of a methanol synthesis catalyst and certain crystalline silicates, as disclosed in German patent application No. 2,518,097 and U.S. Pat. Nos. 4,086,267 and 4,096,163. However, for commercial application is highly desirable to employ a process wherein higher selectivity to products boiling in the gasoline range, i.e., pentanes and higher (C.sub.5.sup.+) is achieved.
In an investigation by Applicants concerning the above-mentioned process it was found that the catalyst mixtures show a higher C.sub.5.sup.+ selectivity according as, in the formula which shows the composition of the silicate, the value of y is lower. It was found that to reach a C.sub.5.sup.+ selectivity which is acceptable for commercial use of the process, y should be at most 0.005.
The invention therefore relates to a process for the preparation of an aromatic hydrocarbon mixture in which a mixture of carbon monoxide and hydrogen is contacted with a mixture of two catalysts of which one is capable of catalysing the conversion of an H.sub.2 /CO mixture into acyclic oxygen-containing hydrocarbons, and the other is a crystalline silicate as defined hereinafter, of which in the formula giving the composition of the silicate, the value of y is at most 0.005.